Press brake with automatically variable length bending tool

ABSTRACT

A press brake for metal sheets is described, comprising a tool for bending the metal sheet; the tool comprising a die and pressure means opposite to said die and adapted to press the metal sheet against the die to determine the bending of the metal sheet. The pressure means comprise a plurality of first segments aligned along the bending direction of the metal sheet and adapted to press said metal sheet against the die. The press brake comprises control means adapted to change the longitudinal dimension of the pressure means; the control means are adapted to individually drive each first segment for its longitudinal sliding along the bending direction of the metal sheet, so that the longitudinal dimension of the pressure means corresponds to the longitudinal dimension of the fold to be carried out on the metal sheet.

FIELD OF THE INVENTION

The present invention relates to a press brake with automaticallyvariable length bending tool.

BACKGROUND OF THE INVENTION

Press brakes adapted to bend metal sheets by exerting a pressure bymeans of a specific tool are known in the prior art. The metal sheets tobe bent may have folded ends and different lengths. The bending toolmust be manually varied to adapt it to the various lengths of the metalsheets.

SUMMARY

It is the object of the present invention to provide a press brake withautomatically variable length bending tool so as to adapt the tool tothe different lengths of the metal sheet.

In accordance with the present invention, said object is achieved by apress brake for metal sheets comprising a tool for bending the metalsheet, said tool comprising a die and pressure means opposite to saiddie and adapted to pressing the metal sheet against the die to determinethe bending of the metal sheet, said pressure means comprising aplurality of first segments aligned along the bending direction of themetal sheet and adapted to press said metal sheet against said die andsaid press brake comprises control means adapted to change thelongitudinal dimension of said pressure means, said control means beingadapted to individually drive each first segment for its longitudinalsliding along the bending direction of the metal sheet so that thelongitudinal dimension of the pressure means corresponds to thelongitudinal dimension of the fold to effectuate on the metal sheet,said pressure means comprising a plurality of second segments, saidcontrol means being adapted to individually drive each second segmentfor inserting it between said first segments so that the second segmentis aligned to the first segments along the bending direction of themetal sheet and so that the longitudinal dimension of the pressure meanscomprising at least one first segment and at least one second segmentcorresponds to the longitudinal dimension of the fold to effectuate onthe metal sheet, characterized in that said control means comprisesfirst means adapted to determine the insertion of at least one secondsegment between two first segments by means of a movement transversal tothe bending direction of the metal sheet, said first means comprisemovement means configured to carry out a combination of a rotationmovement and a translation movement of said at least one second segmentfor inserting said at least one second segment between two firstsegments.

The features and advantages of the present invention will be apparentfrom the following detailed description of a practical embodimentthereof, shown by way of non-limitative example in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a press brake with automatically variable length bendingtool in accordance with the present invention;

FIGS. 2-5 show front views of the press brake in FIG. 1, in which thebending tool takes different lengths according to the length of themetal sheet to be bent;

FIGS. 6-8 show first segments of the bending tool in FIG. 1;

FIGS. 9-10 show second segments of the bending tool in FIG. 1 with adevice for the insertion between the first segments;

FIGS. 11-14 show various steps of inserting a second segment between thefirst segments of the bending tool in FIG. 1;

FIGS. 15-19 show various steps for removing the bending tool in FIG. 1from a metal sheet with edges folded inwards due to folds previouslymade in sequence on the sheet sides adjacent to the side being bent.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-19 show a press brake 1 with a variable length bending tool 10according to the present invention. The bending tool 10 of press brake 1comprises a fixed length die 11 arranged on the lower part 2 of thepress brake along a longitudinal axis A and pressure means 12 arrangedon the upper part 3 of press brake 1 and opposite to die 11. Thepressure means 12 are adapted to press the metal sheet 9 against die 11to make a bend on the metal sheet itself; the bending direction of thesheet coincides with the longitudinal axis A.

The pressure means 12 are associated with a device 100 for changing thelength thereof, i.e. the longitudinal dimension thereof, so as to makeit either slightly smaller than or equal to the longitudinal dimensionof the metal sheet to be bent, i.e. so that the longitudinal dimensionof the pressure means 12 corresponds to the longitudinal dimension ofthe fold to be made on the metal sheet 9. Pressure means 12 comprise aplurality of segments 13 sliding along an upper longitudinal guide 25and shown in greater detail in FIGS. 6 and 7; in particular, guide 25 ishollow and each segment 13 is held in position on guide 25 by thepresence of an upper part 26 inserted into the hollow guide 25. Eachsegment 13 comprises a groove 130 so as to have one end 16 which may bearranged within a U-shaped fold of the edge of metal sheet 9 to be bent.Each segment 13 preferably comprises a flat section 17 on the oppositeside of groove 130 for approaching to the next, adjacent segment 13 ofthe plurality of segments 13.

Device 100 is adapted to drive the longitudinal sliding of segments 13along guide 25. Each segment 13 comprises a longitudinal through hole 18for engaging one of the half guides or longitudinal bars 14′, 14″,arranged one after the other in the bending direction of the metal sheetand longitudinally movable, and an actuator 19, which cooperate for thesliding of segment 13 along guide 25.

The control device 100 comprises a processing unit 200, arranged on thebody of press brake 1 or spaced therefrom, set by a user and adapted tocontrol means 15 and actuators 19; each actuator 19 is individuallycontrolled by the processing unit 200 connected to the actuator by meansof wires. Unit 200 may control either all the actuators 19 of segments13 at the same time or only one or some of them adapted to engage one ofbars 14′, 14″ for sliding on guide 25. In particular, each actuator 19comprises a piston which is movable by means of a cylinder (not shown inthe figures) and may be inserted into one of the holes 20 on bar 14′,14″. Once segment 13 has been blocked on bar 14′, 14″, the bar itselfmay be longitudinally moved so as to longitudinally slide one of or allsegments 13 (FIG. 8); movement means 15 controlled again by the centralunit 200 allow to longitudinally move the bars 14′, 14″.

Bars 14′, 14″ are preferably interrupted in the longitudinal directionby a central empty space 30. All elements 13 have equal length D andsize.

The pressure means 12 comprise another plurality of segments 21; thelength of each segment 21 is different from the other segments 21 of theplurality, i.e. segments 21 have different lengths D1, D2 . . . Dn. Asingle segment 21 or several segments 21 may be inserted betweensegments 13; in particular, the insertion of one of or more segments 21occurs in the central space 30 of the plurality of segments 13. Eachsegment 21 is either shorter or longer than each segment 13. One or moresegments 21 are inserted between part or all of segments 13, if themetal sheet to be bent, in particular the part of the metal sheet to bebent, has a length L which is not a whole multiple of the length D ofsegment 13, i.e. L=n*D+e, where “n” is an integer and “e” is a realnumber complementary to length L. In such as case, one or more elements21 should be inserted to cover the missing distance “e”; e.g. for ametal sheet of length L1, L1=n1*D+Dx where “n1” is an integer and “Dx”is the length of a specially made segment 21.

Each segment 21 has a cross section of the lower part equal to the crosssection of the lower part of segments 13 and is inserted into space 30so as to be longitudinally aligned with the other segments 13.

Each segment 21 is connected to movement means 40 which allow it to beinserted into the central space 30 or moved away from the central space30. The movement means 40, controlled by the unit 200 and better seen inFIGS. 9 and 10, comprise a plate 42 connected to the upper part 3 ofpress brake 1, a motorized rotation joint 44 and a motorized translationjoint 41, 43; plate 42 slides along longitudinal guides 48 integral withthe upper part 3 of press brake 1. The translation joint 41, 43comprises an arm 41 connected to plate 42 by means of the rotation joint44 and a second motorized arm 43, slidingly connected to the first arm41 and connected to segment 21; both the motorized rotation joint 44 andthe motorized translation joint 41, 43 are controlled by the centralunit 200. Arm 41 may rotate on a plane transversal to the bendingdirection of the metal sheet, and arm 43 may translate either downwardsor upwards along arm 41. The movement means 40 shown on the front of thepress brake may also be arranged on the back of the same press brake.

FIGS. 11-14 show the various steps in which a segment 21 is insertedbetween the segments 13 in the central space 30. Starting from acondition in which segment 21 is spaced apart from space 30 (FIG. 11),the central unit 200 controls a downward sliding movement of arm 43 onarm 41 with a downward translation of segment 21 (FIG. 12), a followingrotation of arm 41 of a plane transversal to the bending direction ofthe metal sheet until segment 41 is placed inside space 30, underneaththe segments 13 (FIG. 13), and finally an upward translation of segment21 by means of the sliding movement of arm 43 again on arm 41 until theupper end of segment 21 is arranged within the hollow guide 25 and abutsagainst the upper inner part of the hollow guide itself (FIG. 14). Theinsertion position of segment 21 in space 30 being reached, with theupper part inserted into the hollow guide 25 and aligned with segments13, is indicated by a specific sensor 27 arranged on the inner wall ofthe hollow guide 25 on which the upper part 26 of segment 21 abuts.

Movement means 40, movement means 15 and actuators 19 belong to device100, which is adapted to change the length, i.e. the longitudinaldimension, of the pressure means 12. In particular, device 100 isadapted to change the length of the pressure means 12 in accordance withthe length of the metal sheet 9, thus allowing whether inserting one ormore segments 21 or not, and providing for moving some segments 13 inthe longitudinal direction from the central part 50 where the metalsheet 9 to be bent is arranged.

For example, considering that the pressure means 12 comprise eighteensegments 13 of length D and three segments 21 of different lengths D1,D2 and D3, different combinations are possible according to the lengthof the metal sheet 9 to be bent, as shown in FIGS. 2-5.

For example, if the length of the metal sheet, i.e. the part of metalsheet to be bent, is L1=18*D+D2, the situation shown in FIG. 2 willoccur, in which segment 21 having length D2 is firstly inserted, by themovement means 40 controlled by central unit 200, into the central space30 between the segments 13 of length D equally arranged across segment21, i.e. nine on one side and nine on the other side with respect tosegment 21. Segments 13 then move towards the segment 21 arranged in thecentral space 30 until segments 13 are adjacent to segment 21, so thatthere are no interruptions of the pressure means 12 for bending themetal sheet; said movement is implemented by controlling all actuators19 of segments 13 for the connection to bars 14′, 14″ and the followinglongitudinal movement of bars 14′, 14″ towards the central space 30 bymeans of the movement means 15 controlled by the central unit 200.

If the length of the metal sheet, i.e. the part of the metal sheet to bebent, is L2=10*D+D2, the situation shown in FIG. 3 will occur, in whichsegment 21 having length D2 is firstly inserted, by the movement means40 controlled by the central unit 200, into the central space 30 betweensegments 13 of length D equally across segment 21. Only ten segments 13then move towards the segment 21 arranged in the central space 30, i.e.five segments carried by bar 14′ and five segments carried by bar 14″,until segments 13 are adjacent to segment 21, so that there are nointerruptions of the pressure means 12 for bending the metal sheet; saidmovement is implemented by controlling actuators 19 of the only tensegments 13 for the connection to bars 14′, 14″ and the followinglongitudinal movement of bars 14′, 14″ towards the central space 30 bymeans of the movement means 15 controlled by the central unit 200.Thereby, side interruptions 51, 52 are made in the plurality of segments13 which are especially useful in the case of metal sheets 9 with foldededges.

If the length of the metal sheet, i.e. the part of the metal sheet to bebent, is L3=3*D+D2, the situation shown in FIG. 4 will occur, in whichsegment 21 having length D2 is firstly inserted, by means of themovement means 40 controlled by the central unit 200, into the centralspace 30 between segments 13 of length D equally arranged across segment21. Only three segments 13 then move towards segment 21 arranged in thecentral space 30, i.e. two segments carried by bar 14′ and a segmentcarried by bar 14″, until segments 13 are adjacent to segment 21; saidmovement is implemented by controlling actuators 19 of the only threesegments 13 for the connection to bars 14′, 14″ and the followinglongitudinal movement of bars 14′, 14″ towards the central space 30 bymeans of the movement means 15 controlled by the central unit 200. Theside interruptions 51, 52 are again made in the plurality of segments13.

If the length of the metal sheet, i.e. the part of the metal sheet to bebent, is L4=2*D+D1 the situation shown in FIG. 5 will occur, in whichplate 42 firstly longitudinally translates on the upper part 3 of pressbrake 1 to reach the central space 30 and then segment 21 having lengthD1 is inserted by the movement means 40, controlled by the central unit200, into the central space 30 between the segments 13 of length Dequally arranged across segment 21. Only two segments 13 then movetowards the segment 21 arranged in the central space 30, i.e. onesegment carried by bar 14′ and one segment carried by bar 14″, until thesegments 13 are adjacent to segment 21; said movement is implemented bycontrolling the actuators 19 of the only two segments 13 for theconnection to bars 14′, 14″ and the following longitudinal movement ofbars 14′, 14″ towards the central space 30 by means of the movementmeans 15 controlled by the central unit 200. The side interruptions 51,52 are again made in the plurality of segments 13.

If the length of the metal sheet 9, i.e. the part of the metal sheet tobe bent, is L5=n5*D, i.e. the length of the metal sheet is an exactmultiple of the length D of segment 13, only the necessary segments 13will be moved, i.e. six segments if n5=6, towards the central space 30,i.e. three segments carried by bar 14′ and three segments carried by bar14″, until the segments 13 carried by a bar 14′, 14″ are adjacent to thesegments carried by the other bar 14′, 14″ to totally cover the centralspace 30; said movement is implemented by controlling the actuators 19of the only six segments 13 for the connection to bars 14′, 14″ and thefollowing longitudinal movement of bars 14′, 14″ towards the centralspace 30 by means of the movement means 15 controlled by the centralunit 200. The side interruptions 51, 52 are again made in the pluralityof segments 13.

If the edges of the metal sheet to be bent have a sequence of U-shapedprofile folds on the previously bent adjacent sides, as shown in FIG.15, the problem of extracting the bending tool arises because ofproblems of geometrical fitting. Firstly, the same operations as theprevious cases are carried out, i.e. considering a length of the metalsheet 9 L9=6*D+D2, segment 21 having length D3 is inserted, by means ofthe movement means 40 controlled by the control unit 200, into thecentral space 30 between segments 13 of length D equally arranged acrosssegment 21. Only six segments 13 then move towards the segment 21arranged in the central space 30, i.e. three segments 13 carried by bar14′ and three segments carried by bar 14″, until the six segments areadjacent to segment 21, so that there are no interruptions of thepressure means 12 for bending the metal sheet 9; said movement isimplemented by controlling the actuators 19 of the only six segments 13for the connection to bars 14′, 14″ and the following longitudinalmovement of bars 14′, 14″ towards the central space 30 by means of themovement means 15 controlled by the central unit 200. Thereby, sideinterruptions 51, 52 are made in the plurality of segments 13.

The metal sheet 9 is then inserted, as usual in the working position,under the bending tool so as to obtain a metal sheet 90 with length L90and U-folded edges.

The bending tool is released once the U shaped edges have been made(FIG. 15); the pressure means 12 are vertically lifted to create adistance Z between the lower part of the pressure means 12 and the metalsheet 90 (FIG. 16).

Segment 21 having length D2 is then moved away from the central space 30by the movement means 40 controlled by unit 200. Arm 43 thus slidesdownwards on arm 41 with a downward translation of segment 21 (FIG. 17),a following rotation of arm 41 on a plane transversal to the bendingdirection of the metal sheet until segment 21 is moved away from space30 (FIG. 18), and finally an upward translation of segment 21 again bymeans of sliding arm 43 on arm 41 to return segment 21 to the initialposition in FIG. 10.

Six segments 13 then move towards the central space 30, i.e. threesegments carried by bar 14′ and three segments carried by bar 14″, untilthe length of the pressure means given by the six segments 13 is shorterthan the distance between the opposite ends of the folded edges of themetal sheet 90. Said movement is implemented by controlling theactuators 19 of the only six segments 13 for the connection to bars 14′,14″ and the following longitudinal movement of bars 14′, 14″ towards thecentral space 30 by means of the movement means 15 controlled by thecentral unit 200 (FIGS. 18, 19).

The metal sheet 90 may thus be removed (FIG. 19). An alternative releasemode consists in only moving forward and slightly rotating sheet 90 soas to determine a diagonal space sufficient to extract the pressuremeans 12 in the length composition used for bending.

1. Press brake for metal sheets comprising a tool for bending the metalsheet, said tool comprising a die and pressure means opposite to saiddie and adapted to pressing the metal sheet against the die to determinethe bending of the metal sheet, said pressure means comprising aplurality of first segments aligned along the bending direction of themetal sheet and adapted to press said metal sheet against said die andsaid press brake comprises control means adapted to change thelongitudinal dimension of said pressure means, said control means beingadapted to individually drive each first segment for its longitudinalsliding along the bending direction of the metal sheet so that thelongitudinal dimension of the pressure means corresponds to thelongitudinal dimension of the fold to effectuate on the metal sheet,said pressure means comprising a plurality of second segments, saidcontrol means being adapted to individually drive each second segmentfor inserting it between said first segments so that the second segmentis aligned to the first segments along the bending direction of themetal sheet and so that the longitudinal dimension of the pressure meanscomprising at least one first segment and at least one second segmentcorresponds to the longitudinal dimension of the fold to effectuate onthe metal sheet, characterized in that said control means comprisesfirst means adapted to determine the insertion of at least one secondsegment between two first segments by means of a movement transversal tothe bending direction of the metal sheet, said first means comprisemovement means configured to carry out a combination of a rotationmovement and a translation movement of said at least one second segmentfor inserting said at least one second segment between two firstsegments.
 2. Press brake according to claim 1, wherein all the firstsegments have the same longitudinal dimension.
 3. Press brake accordingto claim 1, wherein each second segment has a longitudinal dimensionlower or higher than each first segment.
 4. Press brake according toclaim 1, wherein said first means comprise a plate longitudinallysliding on a fixed part of the press brake and movement means for eachsecond segment, said movement means comprising a rotation motorizedjoint and a motorized translation joint connected with the secondsegment.
 5. Press brake according to claim 4, wherein said fixed part ofthe press brake is located above said first segments and in that saidpressure means comprises a hollow guide for the arrangement of saidfirst segments and in that said motorized translation joint comprises afirst arm and a second arm sliding connected with the first arm andcarrying at an end said second segment, said movement means determiningsaid insertion of at least one second segment between two first segmentsby sliding directed downward of the second arm on the first arm, byrotation of the first arm by means of a rotation of the rotation jointand sliding directed upward of the second arm on the first arm forinserting said second segment inside the hollow guide of the pressuremeans.
 6. Press brake according to claim 1, wherein said control meanscomprise two longitudinal bars arranged one successive the other alongthe bending direction of the metal sheet and second means adapted tolongitudinally move said two longitudinal bars, each first segmentcomprising a longitudinal through hole for engagement with one of saidtwo longitudinal bars and an actuator, said actuator being adapted toblock the first segment at one of the two longitudinal bars for thelongitudinal sliding of the same first segment.
 7. Press brake accordingto claim 6, wherein said two longitudinal bars are spaced by a emptyspace for the insertion of at least one second segment between said atleast two first segments belong to two bars, said control means beingadapted to control two bars and the relative actuators for thelongitudinal movement of said at least two first segments toward the atleast one inserted second segment until said at least two first segmentsare adjacent to the at least one inserted second segment so thatinterruptions of the pressure means along the bending line of the metalsheet are not present.
 8. Press brake according to claim 1, wherein eachone of said first segments comprises an end adapted to engage with theedges of the metal sheet which are bent in U shape.
 9. Press brakeaccording to claim 6, wherein each one of said first segments comprisesan end adapted to engage with the edges of the metal sheet which arebent in U shape, and said control means, in the case wherein the metalsheet has edges bent in U shape, are adapted to control the first meansso as to go the at least one second segment away from said space betweentwo first segments, said control means being adapted to successivelycontrol said two longitudinal bars and the actuators relative to the atleast two first segments for longitudinally moving said at least twofirst segments toward the space which is left empty by the at least onesecond segment so as to allow the removal of the metal sheet with edgesbent in U shape.
 10. Press brake according to claim 1, wherein saidcontrol means are adapted to place said first segments and said secondsegments adjacent to each other along the bending direction of the metalsheet.